There are a variety of interactive electronic book devices in which a book is placed on a platform. The platform includes a detection system where a generated response depends upon the portion of the book the user points to with a stylus or other pointing device. Such interactive books are sometimes known as “talking books,” although more generally an interactive book may use audio and visual outputs to interact with a user. Commonly, an interactive book device is configured to provide an audio output related to a stylus position. For example, an interactive book device for children may speak the names of words which are pointed to or play games when the child points at a picture. Although interactive books are commonly sold as children's toys, they also have numerous other potential applications as well.
One form of interactive book device utilizes an electronic proximity detection system to detect the position of a stylus relative to a support surface, with the book resting on the support surface such that the stylus is used to point to a region on an open page of the book. This permits a microprocessor or other control element to determine the location of the book to which the user pointed with the stylus. There are several technologies commonly used to electronically sense the position of a stylus. In one approach, the support surface is a conventional graphics tablet and the stylus is a conventional graphics tablet pen. For example, the support surface of an interactive book may comprise a conventional graphics pad having an array of sensing elements that are capacitively or inductively coupled to the stylus. In another approach, the support surface may contain a grid-like array of radiating antennas that are sequentially operated, such that the position of a stylus may be determined by analyzing which of the antenna elements produces the strongest signals in the stylus. Still another approach is an electrographic sensor in which the support surface includes a conductive layer having three or more contacts, with the contacts being pulsed in pairs with an RF signal such that the stylus receives signals traversing at least two different paths, thereby permitting the position of the stylus to be determined using a triangulation algorithm. An electrographic sensor using a triangulation algorithm is described in U.S. Pat. Nos. 5,686,705 and 5,877,458, the contents of which are hereby incorporated by reference.
FIG. 1 is a perspective view of a conventional prior art interactive book device similar to that of U.S. Pat. No. 5,575,659. As can be seen in FIG. 1, a support surface 2 has a graphics tablet 1 upon which a book 3 having open pages 4 and 5 is disposed. A graphics tablet pen 6 is used to point to regions on the open pages of the book. An electrical cable 7 couples graphics tablet pen 6 to graphics tablet 1. The position of the graphics tablet pen 6 relative to the graphics tablet 1 is transmitted via cable 8 to an electronic control element 9 and associated audio device 10 for producing an audio output 12 related to the position of the pen 6. For example, a user may use the pen 6 to point to a region 20 or 22 on an open page. In turn, the electronic control element 9 and audio devices may play a message related to region 20 or 22, i.e., control element 9 utilizes the position data of the graphics tablet to determine a corresponding message or sound to be presented. For example, region 20 or 22 may contain a picture of a cow such that when a user points the pen to region 20 or 22, the control electronics directs the audio device to play a recording of a cow's moo.
In an interactive system of this type, high resolution is desirable so that the user can touch or point a pen to a large number of different pictures, symbols, or words in the book. However, conventional interactive book devices have poor resolution between neighboring regions. There are several physical limitations on the accuracy with which a pointer may be used to point to an area of interest. One limitation is the accuracy of the detection system used. For example, if the graphics tablet has a 3 millimeter resolution, interactive symbols must be more than 3 millimeters apart.
One factor that limits the resolution of conventional interactive book systems is the accuracy with which the pages of a book are positioned relative to the detection system. Conventional devices allow the booklet or document to shift slightly from side to side, thus interfering with resolution. Further, in a conventional system, the pages do not lie flat and evenly on the surface where detection takes place, for example, because the book binding constrains the pages of the book, as shown in prior art FIGS. 1 and 2.
As shown in the illustrative side view of the prior art, in FIG. 2, conventional interactive book devices are limited by the accuracy of using a pointer 240 to point to a specific region on a booklet page because of the inherent flexure of the pages 210, 212, 214, 216, 220, 222, 224, and 226 relative to a binding 230. Each page is slightly curved relative to the underlying support 250. Moreover, the page curvature will depend, at least partially, on how hard and the angle with which a user presses down upon an open page with the pointer. When a user points to, say, point P, the variable curvature of page 210 may result, for example, in point P shifting from a position directly over detector 268 to one between detector 266 and 268 or to a position between detectors 270 and 268. For example, if a user presses the pointer hard upon the page, it will flatten and point P will move transversely towards detector 266. Conversely, if the user applies no pressure, the page will have its maximum curvature and point P may lie closest to detector 270.
In addition to the above problem, in conventional systems, the entire booklet may shift position as the user turns the pages of the book. Referring again to FIG. 2, forces are transmitted to binding 230 from the act of turning the open pages. These forces can act to move binding and shift the entire book relative to the support and detection system it houses.
Another drawback with conventional interactive books is that the user must remember to point to particular location indicia or symbols on each page of the book so that the audio signals can be correctly associated with the symbols and text on a particular page. For example, the symbol may be a fish on one page, a bird on another, and a tiger on another page. Each location indicia or symbol is placed on a different sub-region along a border region of each page. However, if the user forgets to touch the pointer to the required location symbol, the control electronics may be confused regarding which page is open. Other than a written instruction, there is no way to remind the user of the need to touch the page-noting symbol with the pointer so a child who forgets to turn the page is only confronted with the audio signals that do not correspond to the images.
Embodiments of the invention address these and other problems.